Dry cleaning apparatus and method



Aug. 31, 1965 INVENTORS JOHN R. YOUNG, RALF B. TRUSLER,

BY ALOYSIUS X.HILTGEN 8. WILLIAM H. MATZ WMM@% ATTORNEYS United States Patent Office 3,203,754 Patented Aug. 31, 1965 3,203,754 DRY CLEANING APPARATUS AND METHOD John R. Young and Ralf B. Trusler, Dayton, Ohio, and Aloysius X. Hiitgen, Coraopolis, and William H. Matz, Pittsburgh, Pa; said Young and said Trusler assignors to The Davies-Young Soap Company, Dayton Ohio, a corporation of Ohio, and said Hiltgen and said Matz assignors to Pittsburgh Chemical 'Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 29, 1962, Ser. No. 183,551 7 Claims. (Ci. 8-142) This application is a continuation-in-part of our earlier applications Serial Nos. 92,915 and 97,038, filed March 2, 1961, and March 20, 1961, respectively, now abancloned.

This invention relates to a dry cleaningapparatus and more particularly to an improved apparatus whereby discoloration of the dry cleaning solution is minified.

During operation of dry cleaning equipment, the dry cleaning solvent or solution ultimately becomes dye discolored as a result of bleeding of some of the dye from some of the fabrics being cleaned. Such discoloration is objectionable since it may cause a change in color or staining of the relatively light colored fabrics which may absorb some of the dark dye present in the cleaning solution. Moreover, discoloration of the solvent is caused by solvated dirt which is removed from the fabrics, and' this source of discoloration in addition to that produced by solvating or leaching some of the dye may cause the cleaning solution to become quite dark.

Additionally, the articles being cleaned may contain odor bearing solids such as fatty acids and the like which :are soluble in the cleaning solvent. Such odor bearing material, as it dissolves in the solvent, tends to discolor it to some extent, and may impart noticeable odor thereto which may then in turn deposit and remain on some of the articles.

One method of removing the discoloration attributable to soluble dyes and other sources of objectionable color and odor involves shut-down of the equipment and treatment of the solvent to remove the discoloration. The clean-up operation is normally performed at least once a day in commercial cleaning units, and may be performed two or more times a day depending on the nature of the articles cleaned, the dye employed in the articles and the amount of discoloration of the solvent resulting from other causes.

A primary object of this invention is the provision of an improved dry cleaning apparatus wherein the dry cleaning solution may be maintained in a condition such that discoloration thereof is at a relatively low level whereby staining of the lighter colored fabrics is avoided.

In the improved apparatus of the present invention, the dry cleaning solvent is maintained at a substantially low level of fatty acids and discoloring materials by a color and odor adsorption or removal assembly containing an agent which is maintained in a static nondispersed condition during contact with the solvent. In this manner, the dry cleaning solution or solvent is maintained free of suspended color removal agent thereby eliminating the use of centrifuges or similar type devices which may be required to separate the solution and any color removal agent or material which may be suspended therein. Since the color and/or odor removal agent is maintained in a static as opposed to a dynamic condition, the agent is not carried along with the solution and thus contact between the agent and garments present in the cleaner is avoided.

Another object of this invention is the provision of a novel cleaning apparatus including an assembly for removing a material amount of discoloration from a portion of the cleaning solution whereby a continuous source of cleaning solution is available having a materially reduced color content for effecting material reduction of the color content in the total amount of cleaning solution.

It is also an object of this invention to provide a novel color adsorption assembly for use with a dry cleaning apparatus whereby discoloration of the cleaning solution attributable to solvated dyes and other causes may be substantially reduced without shut-down of the apparatus or interference with the cleaning action thereof.

Another object of this invention is the provision of a novel method of removing objectionable discoloration from dry cleaning solutions without materially affecting continuous operation of the dry cleaning apparatus.

A further object of this invention is the provision of a color and odor removal assembly for use with a dry cleaning assembly wherein the dry cleaning solution is flowed through and in contact with a granular color and odor removal agent which is maintained in a static or non-dispersed condition in the presence of the dry cleaning solution.

It is still a further object of this invention to provide a dry cleaning apparatus wherein :a portion of the dry cleaning solution is circulated through a color removal column during operation of the apparatus for removing a material amount of the objectionable color from the portion, and wherein the discoloration free cleaning solution is intermixed with discolored cleaning solution for progressively and continually reducing the overall color content of the cleaning solution during operation of the cleaning apparatus.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawing: FIG. 1 is a schematic View of a prior art cleaning apparatus;

FIG. 2 is a schematic view of a cleaning apparatus constructed in accordance with the present invention; and

FIG. 3 is a view partly in section and partly in elevation of the color removal column constructed in accordance with the present invention.

The prior art cleaning apparatus shown in simplified form in FIG. 1 includes a cleaning assembly 10 having a door 12 for allowing insertion and removal of soiled articles into an agitator drum 14 which tumbles the articles to be cleaned much in the same fashion as a conventional washing machine. Dry cleaning fluid or solvent such as Stoddard Solvent or perchloroethylene, or the like, is introduced into the assembly 10 by an input conduit 15. Generally a detergent is utilized in amounts of about 0.2 to 4% in addition to about 0.05% to 5% water in order to promote better cleaning. In the case of perchloroethylene, about 2% of a neutral salt of a petroleum sulfonate, such as Pe-trosol #745, may be utilized 'as a detergent, while in the case of hydrocarbon solvents about 4% of a detergent produces satisfactory reuslts. Located in the output conduit 17 connected at [the base of cleaning assembly 10 is a pump 20, or other suitable recirculating means, which withdraws the cleaning solution from the assembly 10 and feeds it to a filter unit 25.

The filter unit 25 includes a plurality of filter leaves 26 each of which is formed by covering a relatively fine wire mesh, tube, cloth, or other liquid pervious member with diatomaceous earth. The flow of cleaning solution is through the earth coating and down through the center of each of the leaves 26 to a manifold 27 which interconnects and supports all the leaves, and which in turn is connected to the inlet line 15. The filter unit may be as above described or of any construction well known in the art, and serves to remove any solid material dispersed in the solvent.

In operation, soiled articles are placed in the drum 14, the door is closed and a cleaning cycle is started. During the cleaning cycle, solvent is continuously recirculated through the system and through the filter unit 25 to effect removal of any solid material such as dirt, lint particles or other matter suspended in the cleaning solvent. In addition to removing the dirt and the like during each cycle, the cleaning solution acts as a solvent, to some extent, for some of the dyes employed in the articles being cleaned. In addition to this source of discoloration, some of the dirt removed from the soiled articles is in the form of solvent soluble material which acts to discolor the cleaning solvent. As was noted previously, the cleaning solution also acts to render soluble odor bearing materials such as fatty acids which add to the discoloration and impart an odor to the solvent which may be carried to other articles in the cleaning drum. Ultimately, during the use of the cleaning solution, a point is reached where discoloration of the solvent is such that it may be harmful to any light colored fabrics which are exposed to the relatively dark discolored cleaning solvent.

The change in color from water clear or slightly yellow, which is the color of the cleaning solution in the preferred condition, to dark brown, for example, may be checked by the operator during the succession of cleaning cycles. Means in the form of sight glasses 30 and 31 positioned in the outlet line 17 and inlet line 15, respectively, are provided to enable observance of the condition of the dry cleaning solvent attributable to discoloration. When the discoloration reaches a point where it may become harmful to light colored fabrics, the cleaning solvent is treated to remove the discoloration. In this connection, it should be noted that the diatomaceous earth coating on the filter leaves is itself ineffective in removing signifcant amounts of discoloration or odor bearing materials from the solvent.

Heretofore, one procedure for cleaning the solvent involved shut-down of the cleaning apparatus and removal of all of the articles or garments from the drum 14. With the articles removed, approximately one or two pounds, depending on the size of the unit, of finely divided carbon is introduced in the drum 14. The cleaning apparatus is activated to start another cycle, and the cleaning fluid is circulated through the closed loop system as above described. As the fluid contacts thecarbons, a portion of the carbon is progressively dispersed in the solvent to effect removal of odor and discoloring ingredients. The carbon is then carried to the filter 25 where it deposits on the diatomaceous coating on the filter leaves. As the cleaning solution discolored by solvated dye, dirt, and odor bearing material is in contact with the dispersed carbon, the discoloration and odor is absorbed by the carbon and removed from the solvent. The recycling process is continued until all the carbon has been collected on the diatomaceous earth, and the dark color present in the solvent is removed as can be observed through the sight glasses 30 and 31.

Subsequent to this clean-up operation, the carbon remains on the filter leaves in a condition of reduced activity incapable of removing any additional significant amounts of dscoloration since the carbon will become color saturated in a relatively short time after admixture with the solvent. The dry cleaning apparatu may then be operated until the color of the solvent indicates that a harmful amount of dye or other discoloration is present therein, at which time the apparatus must be shut-down for an additional clean-up. With most equipment operated at an average number of cycles per day, it is necessary to perform such a clean-up operation at least once and possibly twice a day thereby necessitating shut-down for the reconditioning process above described.

The main disadvantage of the clean-up operation above described is the fact that the carbon material employed is difficult and troublesome to handle. The carbon heretofore employed has been an extremely finely divided material having a flour-like consistency, and the success of clean-up depends to a great extent upon the ability of the carbon to be carried by the solvent and intermixed therewith. Additionally, the carbon must be fine enough to be carried through the pump without significantly interfering with the pump action by formation of deposits, mechanical binding and other similar action. A finely divided carbon is employed for a second and more important reason, that is, the carbon is capable of being carried by the solvent and removed therefrom by being deposited on the filter leaves. In this way, redispersion of the powdery material through the system is avoided.

Due to the fact that the carbon is placed in the drum 14, there is always a danger that some of the carbon will remain therein and cause spotting or streaking of the articles introduced into the drum during a cleaning cycle. Moreover, the extremely fine nature of this carbon may render removal of carbon spots from the garments a difficult procedure, and in some instances, such spotting or staining has occurred to such. an extent as to render the article unserviceable. Additionally, the carbon remains on the filter leaves in the filter unit 25, and there is always a danger that a crack or other mechanical flaw in any of the leaves will allow the passage of carbon into the cleaning drum 14 and cause damage to the articles, as above described.

An additional disadvantage of the above system relates to the considerable variation in the discoloration level of the cleaning solution. For example, after a clean-up operation the solvent is substantially free of interfering amounts of discoloration, and the articles cleaned immediately after clean-up appear bright and fresh looking. In contrast to this, the solvent immediately prior to the clean-up operation may contain sutlicient interfering discoloration to reduce, to a noticeable extent, the brightness, clarity and freshness of the cleaned article. Thus, it can be seen that between clean-up operations the discoloration level varies between a minimum and a maximum and never remains at a relatively uniform low level.

The above as well as other disadvantages have been substantially eliminated in accordance with the present invention, a preferred embodiment of which is shown in FIG. 2 wherein the same reference numerals have been employed to identify elements corresponding to those shown in FIG. 1. cooperatively associated with the dry cieamng apparatus are means 35 in the form of a color and odor removal assembly connected in a parallel circult between the filter unit and the inlet line 15 forming a continuous supply of cleaning solvent of reduced discoloration level. Liquid flowing through the absorptron unit has a noticeable amount of the discoloration removed therefrom and is preferably ported to the intake side of pump 20 in the output line 17 by conduit 36.

It is preferred that a portion of the solvent leaving the filter tank be diverted through the color adsorption assembly and fed into the uncleaned solvent leaving the cleaning apparatus 10. To this end means including a mono-flow supply T connection 38 are provided to tap off continuously, during the operation of the cleaning apparatus, preferably approximately 5 to of the solvent flowing through the inlet line from the filter unit 25. In the place of a mono-flow supply T, any suitable valve or metering device may be employed, as is well known in the art; however, it is preferred that a mono-flow T be employed for simplicity of construction and reduction in installation expenses. Experience has indicated that removal of significantly less than 5% of the flow of solvent may not produce satisfactory reduction in the rate of the discoloration, while removal of an excess substantially greater than about 50% interferes with cleaning of the articles in the drum 14. Accordingly, it is preferred that about 10 to 20% solvent be continuously circulated r through the color removal unit since removal of such an into the column.

amount does not materially interfere with the overall cleaning action and operates to provide a sufficient amount of solvent of reduced color content to maintain the total amount of solvent in the system at a materially reduced discoloration free condition.

It is to be understood that if color removal is to be carried on simultaneously with a cleaning cycle, as above described, a sufiicient amount of cleaning solvent should be circulated through the cleaning drum 14 to insure proper cleaning action. Experience with existing commercial units has indicated that flow of about 5% to 50% of the solvent from filter unit through the parallel loop including the color removal assembly and conduit 36 provides satisfactory color reduction and does not materially interfere with the cleaning action of the apparatus. Moreover, the rate of discoloration of the solvent may vary from one installation to the next, and the amount of solvent flowed through the color removal assembly may be varied to suit the requirements of the installation, provided the flow rate through the color removal unit is sufiicient to accomplish the desired degree of color reduction without materially interfering with the cleaning action of the apparatus.

The color removal assembly preferably includes a cylindrical tank 40, as shown in FIG. 3, fabricated of a liquid impervious material which is chemically inert with respect to the solvent and possesses a suflicient amount of mechanical strength to support the weight of the color removal agent and solvent which substantially fills the tank 40. The color and odor removal agent 45 may be above mesh in size and smaller than 4 mesh, and it is to be noted that commercially available materials normally include a distribution of particles of several sizes.

It is preferred to employ granulated carbon having a particle size as set forth above since the granules are small enough to provide a maximum amount of adsorption of the color from the solvent, and yet large enough to prevent any caking which would tend to take place if the granular particles were of too small a size. It has been noted with relatively fine particles that caking tends to take place to form a solvent impervious barrier which significantly reduces the flow rate of the solvent through the color clarification column.

Located in the top of the column 40 is a removal bung 46 which facilitates introduction of the granular material In the base 47 of the column there is provided a removal plug 49 employed to provide access for withdrawing the spent color adsorption agent. It is a relatively simple matter to recharge the column with a new charge of color removal agent by removing the plug 49 and allowing the granules to come out through the base of the column. The plug is reinserted and tightened and an additional charge is inserted through the removal bung 46 located at the top of the column. Positioned in the base 47 of the tank 40 is a finger 5 in the form of a mesh screen supported by suitable reinforcing members or a self-supporting plate through which the solvent may flow after it has passed through the color removal agent 45 in the tank. The mesh size or the size of the apertures in the plate should be small enough to 6 affixed to the lower end of the finger 50. Since the granular color clarification agent is larger in mesh size than the openings in the finger, little if any of the granular material is carried into the line 36 and the remaining solvent in the system.

The mono-flow T 38 is of conventional design including a battle element 51 positioned so as to intercept the flow of solvent into conduit 53 as shown in FIG. 3. By appropriate selection of pipe diameters, approximately 10 to 15% of the flow in conduit 53 may be diverted through the color clarification column. For example, a 2" x 2" x T joint, or a 1%" to 1 /2" conduit with a /z" outlet, or a 1" pipe with a Vs" outlet having a monofiow T joint provides the desired flow rate through the color clarification column.

It is preferred due to flow characteristics that the flow of solvent through the clarification column 35 be downward so that the color laden solvent will contact a maximum number of granular particles contained in the column 35. To this end the column is arranged at with respect to the horizontal, although it is understood that the column may be arranged at 45 or 30 with respect to horizontal if installation conditions require such an arrangement.

Excellent results have been achieved in removing color and odor bearing materials from the solvent by utilizing granular carbon materials having a surface area between 600 and 1300 square meters per gram, a molasses value or number of to 400 and a CWS hardness or abrasion resistance to 50 to 98. The molasses value and the CWS hardness may be measured as described in the patent t Zabor 2,763,580 issued September 18, 1956.

In a preferred form, the carbon has a surface area of about 950 to 1050 square meters per gram, a molasses value of between 200 and 250 with a CWS hardness of about 80 to 90. It is preferred that a material having a bulk density of between .43 and .50 grams per cc. be

utilized since such a material is sufiiciently hard to be 25% even in those instances in which the efficiency of the granular agent as a color removal meduim has been markedly reduced due to the prolonged use thereof. Such removal of the fatty acids is believed possible due to the presence of oxides or silicates of magnesium, calcium, and/or aluminum in granular carbon.

In any event, it is desirable in accordance with the present invention to utilize the sweetener or a fatty acid removal material having an alkalinity range of from pH of 7.4 to a pH of about 9.5 as measured by a pH electrometer using approximately 5 grams of the metal compound in about 50 grams of distilled water. Typical alkaline materials which have been found satisfactory are the oxides, hydrated oxides and silicates of magnesium, calcium, and/or aluminum either individually or mixed with one another. The sweetener material, which is preferably granular in form, may be added and intermixed with the granular carbon material in amounts between 2 and 50% by weight, although his preferred that 4 to 15% of the sweetener be added such that the color removal characteristics of the resultant composition are maintained at a relatively high level. In this manner, the fatty acid content in the dry cleaning solution may be maintained at a level of about .09% and not exceeding about 0.25%. A sweetener is utilized having a hardness not less than 1 /2 as determined by Mohs scale of mineral hardness and preferably having a particle size from about 4 to 60 mesh. The resultant mixture of sweetener and granular carbon material possesses a bulk density such that it will remain in a static condition during periods of contact with the solvent, and thus, the granular color and odor removal agent will not become dispersed in the solvent.

In operation, a selected portion of the color contaminated solvent is continually recycled through the color clarification column 35, as described above. With each pass of the liquid a noticeable amount of the objectionable color is withdrawn, and the solvent of reduced color content is intermixed with color laden solvent leaving the cleaning drum 14 to effect appreciable reduction in the overall color content of the solvent. During continued operation of the apparatus, an increasing amount of color is removed until a point is reached where the level of interfering discoloration in the solvent is at a relatively uniform low level. In this relatively uniform low level the solvent exhibits a light yellow or amber color. During operation of the cleaning apparatus, color is being continually removed by the color clarification column 35 so that the discoloration level is maintained at a relatively low level. Ultimately, a point is reached it which the color removal agent becomes saturated, at which time it is necessary to remove the spent agent and recharge the colmn. In normal use, it is necessary to recharge the column about once every two to three weeks with about to pounds of a color clarification agent of the type above described.

As will be apparent from the above description, the primary advantage of the apparatus constructed in accordance with the present invention is the uniform low level of discoloration and the fact that the apparatus is not involved in shut-down in order to clean-up the solvent. An additional advantage is the fact that color clarification agent is maintained out of contact with the cleaning drum since it is granular in form and is not circulated through the system along with the solvent as was the case with the prior art devices.

To illustrate the above point, let us consider the events taking place after the column has been recharged with fresh color clarification agent. In the charge initially placed in the column there is present a relatively small amount of particles ranging in size below microns due to agitation of the granular material during shipment and the like. As the apparatus is started for a cleaning cycle, solvent is introduced into the color clarification column and any small particles are carried along with the solvent through the conduit 36 and outlet line 17. The solvent With the relatively small particles is carried by conduit 17 into the filter element 25 where relatively small amounts of solid carbon are deposited on the filter element. The particle free solvent is then introduced into inlet line 15 and from there to the drum 14, and a portion of the solvent is taken off through the color clarification column, as above described.

It can be seen that the solvent leaving the color clarification column is ported directly to the outlet line and thus by-passes the cleaning drum, and therefore, none of the color clarification agent is ever directly introduced into the cleaning drum. By this procedure, any marking or staining of garments and other articles present in the cleaning drum by residual finely divided carbon is avoided. Due to the presence of the filter unit 25, any solid material carried into the outlet line 17 is removed prior to introduction of the solvent into the drum through conduit 15.

In some instances, it may be desirable to clean-up the solvent at a relatively fast rate, in which instance means may be provided for circulating all of the solvent through the color clarification column and by-passing the flow through the cleaning drum 14. This may be conveniently accomplished by placing a valve in the inlet line 15 and flowing all of the solvent through the color clarification column 35, through the conduit 36, into the oulet line 17 and through the filter assembly 25. In this 8 manner, color removal is accomplished at a relatively rapid rate without introducing any of the solvent into the cleaning drum thereby eliminating the possibility of harmful deposits of carbon in the cleaning drum 14.

Another aspect of this invention relates to the provision of a pre-packaged granular material which may be easily assembled within the column without excessive handing of the granular material itself. Such a package is preferably fabricated of a liquid pervious material such as muslin and the like, containing a sufficient amount of granular material to occupy a substantial volume of the interior of the column. With such a package, the fingers may be replaced by a perforate screen or plate supported in spaced relation to the bottom of the column. Removal or replacement of the granular material may be accomplished by providing a removable head on the column. It is also within the scope of this invention to provide a perforated basket or container for the granular material which may be removed from the column and wherein the mesh size of the basket is of the order previously mentioned for retaining the granular material therein. With this unit, the basket is removed from the column and the spent granular material emptied from the basket. A new charge is introduced into the basket and the basket reinserted into the column.

The apparatus above described provides an efficient dry cleaning apparatus wherein it is possible to maintain the dry cleaning solvent or solution at a relatively low level of discoloration. It may be installed in existing dry cleaning units in a relatively simple manner or it may be incorporated into newly constructed units. By employing a color clarification agent which is granular in form and which need not be replenished at daily intervals, considerable advantages are achieved by minimizing shut-down, handling of obnoxious finely divided powders, as has been above described. Additionally, the color clarification agent is maintained out of contact with the cleaning drum thereby reducing the possibility of staining or otherwise damaging articles which may be present in the drum.

While the forms of apparatus and the method herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus and this method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A dry cleaning apparatus comprising a cleaning assembly for receiving articles to be treated with a dry cleaning solution, said assembly having inlet and outlet means through which the solution is flowed, a filter for removing solid material, recirculating means and conduits connected between said cleaning assembly and said filter providing a closed loop system for flow of the solution through said filter and said cleaning assembly, a color removal device operable to remove discoloring ingredients from the solution, means connecting said color removal device to form a by-pass of a portion of said loop system through which at least a portion of discolored solution is passed and returned in clarified form to the system, said color removal device including a color removal agent maintained in static condition during passage of said solution therethrough, said color removal agent being composed of a granular carbon having a particle size between about 4 and about 60 mesh and having a surface area between about 600 and about 1300 square meters per gram, a molasses number .of between about and about 400, and an abrasion resistance between about 50 and about 98, and said static condition of said agent cooperating with said filter to prevent introduction of said agent into said cleaning assembly and subsequent contact with the articles to be cleaned.

2. A dry cleaning apparatus as set forth in claim 1 in which said granular carbon has a surface area of between about 950 and about 1050 square meters per gram, a molasses number of between about 200 and about 250, an abrasion resistance of between about 80 and about 90, and a bulk density of 0.43 and 0.50 grams per cubic centimeter.

3. A dry cleaning apparatus comprising a cleaning assembly for receiving articles to be treated with a dry cleaning solution, said assembly having inlet and outlet means through which the solution is flowed, a filter for removing solid material, recirculating means and conduits connected between said cleaning assembly and said filter providing a closed loop system for flow of the solution through said filter and said cleaning assembly, means forming a supply of cleaning solution of reduced color content, said supply means including a color removal unit connected to form a by-pass of at least a portion of said loop system through which approximately about to 50% of the total amount of said solution is flowed, means connecting the output of said removal unit to said loop system for returning the solution in clarified form to the system and maintaining the discoloration of the solution in said system to a minimum, a granular color and odor removal agent maintained in a static condition within said unit during flow of solution therethrough, said color removal agent being composed of a granular carbon having a particle size between about 4 and about 60 mesh and having a surface area between about 600 and about 1300 square meters per gram, a molasses number of between about 0 and about 400, and an abrasion resistance between about 50 and about 98, and means for flowing said solution through said unit and around said granular agent while maintaining said agent in a non-dispersed condition.

4. An assembly for removing colors and odors from dry cleaning solvent comprising a chamber portion having inlet and outlet means for flowing the solvent therethrough, decolorizing and purifying material positioned within said chamber and maintained therein in a static condition during flow of solvent through said chamber, said deco-lorizing and purifying material being a granular activated carbon having a particle size between about 4 and 60 mesh, a surface area of between about 600 and about 1300 square meters per gram, a molasses number of between about 150 and about 400, and an abrasion resistance between about 50 and about 98.

5. An assembly as set forth in claim 4 wherein said granular activated carbon has a surface area of between about 950 and about 1050 square meters per gram, a molasses number of between about 200 and about 250, an abrasion resistance of between about 80 and about 90, and a bulk density of 0.43 and 0.50 grams per cubic centimeter.

6. A clarifying unit for use with dry cleaning solvent comprising a central chamber portion including inlet and outlet means for flowing solvent therethrough, a decolorizing and purifying material positioned within said chamber and maintained therein in static condition during flow of said dry cleaning solvent therethrough, said material including a mixture of a granular carbon and a sweetener, said sweetener selected from the group consisting of the oxides, hydrated oxides and silicates of magnesium, calcium and aluminum, and mixtures thereof, said sweetener being present in about 5 to 50% of said mixture and having a hardness not less than 1 /2 as determined by the Mohs scale of mineral hardness and a particle size of from 4 to mesh and exhibiting an alkalinity of pH 7.4 to 9 when tested with a pH electrometer using approximately 5 grams of the sweetener and 50 grams of distilled water, said granular carbon having a particle size between about 4 and about 60 mesh, a surface area of between about 600 and 1300 square meters per gram, a molasses number between about and 400, and an abrasion resistance of between about 50 and about 98.

7. A method of clarifying dry cleaning solvent wherein the solvent is flowed during operation thereof in a closed loop system including a cleaning assembly and a filter for removing solids, comprising the steps of continuously flowing at least 5% to 50% of said solvent flowing from the filter through a granular color and odor adsorbing agent of granular carbon to remove at least a portion of the color and odor therein, maintaining said granular carbon in a static non-dispersed condition during contact with said solvent, and intermixing the solvent of reduced color and odor content with the discolored solvent flowing from the cleaning assembly for progressively reducing the color and odor content of all of the solvent and for substantially eliminating contamination of said cleaning assembly by said granular adsorbing agent, said granular carbon having a particle size between about 4 and about 60 mesh, a surface area of between about 600 and 1300 square meters per gram, a molasses number between about 150 and 400, and an abrasion resistance of between about 50 and about 98.

References Cited by the Examiner UNITED STATES PATENTS 1,545,091 7/25 Flowers 8142 2,317,026 4/43 Brown et al 210-39 X 2,910,137 10/59 Victor 6818 X OTHER REFERENCES Hassler, Active Carbon, pages 45-46, 1941, Githers- Sohl Corp., N.Y.

NORMAN G. TORCHIN, Primary Examiner.

MORRIS O. WOLK, Examiner. 

1. A DRY CLEANING APPARATUS COMPRISING A CLEANING ASSEMBLY FOR RECEIVING ARTICLES TO BE TREATED WITH A DRY CLEANING SOLUTION, SAID ASSEMBLY HAVING INLET AND OUTLET MEANS THROUGH WHICH THE SOLUTION IS FLOWED, A FILTER FOR REMOVING SOLID MATERIAL, RECIRCULATING MEANS AND CONDUITS CONNECTED BETWEEN SAID CLEANING ASSSEMBLY AND SAID FILTER PROVIDING A CLOSED LOOP SYSTEM FOR FLOW OF THE SOLUTION THROUGH SAID FILTER AND SAID CLEANING ASSEMBLY, A COLOR REMOVAL DEVICE OPERABLE TO REMOVE DISCOLORING INGREDIENTS FROM THE SOLUTION, MEANS CONNECTING SAID COLOR REMOVAL DEVICE TO FORM A BY-PASS OF A PORTION OF SAID LOOP SYSTEM THROUGH WHICH AT LEAST A PORTION OF DISCOLORED SOLUTION IS PASSED AND RETURNED IN CLARIFIED FORM TO THE SYSTEM, SAID COLOR REMOVAL DEVICE INCLUDING A COLOR REMOVAL AGENT MAINTAINED IN STATIC CONDITION DURING PASSAGE OF SAID SOLUTION THERETHROUGH, SAID COLOR REMOVAL AGENT BEING COMPOSED OF A GRANULAR CARBON HAVING A PARTICLE SIZE BETWEEN ABOUT 4 AND ABOUT 60 MESH AND HAVING A SURFACE AREA BETWEEN ABOUT 600 AND ABOUT 1300 SQUARE METERS PER GRAM, A MOLASSES NUMBER OF BETWEEN ABOUT 150 AND ABOUT 400, AND AN ABRASION RESISTANCE BETWEEN ABOUT 50 AND ABOUT 98, AND SAID STATIC CONDITION OF SAID AGENT COOPERATING WITH SAID FILTER TO PREVENT INTRODUCTION OF SAID AGENT INTO SAID
 7. A METHOD OF CLARIFYING DRY CLEANING SOLVENT WHEREIN THE SOLVENT IS FLOWED DURING OPERATION THEREOF IN A CLOSED LOOP SYSTEM INCLUDING A CLEANING ASSEMBLY AND A FILTER FOR REMOVING SOLIDS, COMPRISING THE STEPS OF CONTINUOUSLY FLOWING AT LEAST 5% TO 50% OF SAID SOLVENT FLOWING FROM THE FILTER THROUGH A GRANULAR COLOR AND ODOR ADSORBING AGENT OF GRANULAR CARBON TO REMOVE AT LEAST A PORTION OF THE COLOR AND ODOR THEREIN, MAINTAINING SAID GRANULAR CARBON IN A STATIC NON-DISPERSED CONDITION DURING CONTACT WITH SAID SOLVENT, AND INTERMIXING THE SOLVENT OF REDUCED COLOR AND ODOR CONTENT WITH THE DISCOLORED SOLVENT FLOWING FROM THE CLEANING ASSEMBLY FOR PROGRESSIVELY REDUCING THE COLOR AND ODOR CONTENT OF ALL OF THE SOLVENT AND FOR SUBSTANTIALLY ELIMINATING CONTAMINATION OF SAID CLEANING ASSEMBLY BY SAID GRANULAR ADSORBING AGENT, SAID GRANULAR CARBON HAVING A PARTICLE SIZE BETWEEN ABOUT 4 AND ABOUT 60 MESH, A SURFACE AREA OF BETWEEN ABOUT 600 AND 1300 SQUARE METERS PER GRAM, A MOLASSES NUMBER BETWEEN ABOUT 150 AND 400, AND AN ABRASION RESISTANCE OF BETWEEN ABOUT 50 AND ABOUT
 98. 